Gravity from entropy: A radical new approach to unifying quantum mechanics and general relativity

Amazing stuff! Could this be a breakthrough!

What is also very unusual is that this new theory has only one author!

"... For decades, physicists have struggled to reconcile the principles of quantum mechanics with those of general relativity. While quantum mechanics governs the behaviour of particles at the smallest scales, general relativity describes the force of gravity on cosmic scales. Unifying these two frameworks has been one of the most elusive goals in modern science. ...

by treating the metric of spacetime, a key concept in general relativity, as a quantum operator. This innovative approach uses quantum relative entropy, a concept from quantum information theory, to describe the interplay between spacetime geometry and matter. ..."

From the abstract:

"Gravity is derived from an entropic action coupling matter fields with geometry. The fundamental idea is to relate the metric of Lorentzian spacetime to a quantum operator, playing the role of an renormalizable effective density matrix and to describe the matter fields topologically, according to a Dirac-Kähler formalism, as the direct sum of a 0-form, a 1-form and a 2-form. While the geometry of spacetime is defined by its metric, the matter fields can be used to define an alternative metric, the metric induced by the matter fields, which geometrically describes the interplay between spacetime and matter.

The proposed entropic action is the quantum relative entropy between the metric of spacetime and the metric induced by the matter fields. The modified Einstein equations obtained from this action reduce to the Einstein equations with zero cosmological constant in the regime of low coupling.

By introducing the G-field, which acts as a set of Lagrangian multipliers, the proposed entropic action reduces to a dressed Einstein-Hilbert action with an emergent small and positive cosmological constant only dependent on the G-field. The obtained equations of modified gravity remain second order in the metric and in the G-field. A canonical quantization of this field theory could bring new insights into quantum gravity while further research might clarify the role that the G-field could have for dark matter."

From the conclusions:

"This work proposes a modified theory of gravity emerging from statistical mechanics and information theory action. The fundamental idea of this theory is to associate the metric to a quantum operator, playing the role of a renormalizable and effective density matrix. In particular two metrics are discussed: the metric of spacetime that fully defines its geometry and the metric induced by matter fields that are effectively curving the space. The interplay between geometry of spacetime and matter fields is explicitly captured by the proposed action given by the quantum relative entropy between the metric and the metric induced by the matter fields.

Here a Lorentzian theory consistent with this fundamental physical interpretation of gravity is formulated. In order to do this we have built the necessary mathematical background to define the entropy and the cross-entropy of metric tensors in a Lorentzian well defined way. A modified gravity is emerging from this framework when the matter fields are described by topological Dirac-Kähler bosons formed by the direct sum between a 0-form, a 1-form and a 2-form and the induced metric also depends on the curvature of spacetime. The modified Einstein equations reduce to the Einstein equations in the regime of low coupling. By introducing the G-field we obtain the modified Einstein equations and the equations of motion for the matter and the G-field. From this theory it emerges that the proposed entropic action takes the form of a sum between a dressed Einstein-Hilbert action and a matter action. Interestingly, the dressed Einstein-Hilbert action displays an emergent positive cosmological constant that only depends on the G-field. Moreover, thanks to the introduction of the G-field, the equations of modified gravity remain second order in the metric, in the matter and in the G-field. ..."

Gravity from entropy: A radical new approach to unifying quantum mechanics and general relativity

Gravity from entropy: A radical new approach to unifying quantum mechanics and general relativity (original news release) "In a new study ... proposes a groundbreaking new framework that could revolutionise our understanding of gravity and its relationship with quantum mechanics."

Gravity from entropy (open access)

Diagrammatic representation of the entropic quantum gravity action. The action for gravity is given by the quantum relative entropy between the metric of the manifold and the metric induced by the matter field and the geometry.